202807-44-1Relevant articles and documents
Cobalt-Catalyzed Enantioselective C–H Arylation of Indoles
Ackermann, Lutz,Jacob, Nicolas,Oliveira, Jo?o C. A.,Wencel-Delord, Joanna,Zaid, Yassir
supporting information, p. 798 - 806 (2022/02/03)
Atropoisomeric (hetero)biaryls are scaffolds with increasing importance in the pharmaceutical and agrochemical industries. Although it is the most obvious disconnection to construct such compounds, the direct enantioselective C–H arylation through the concomitant induction of the chiral information remains extremely challenging and uncommon. Herein, the unprecedented earth-abundant 3d-metal-catalyzed atroposelective direct arylation is reported, furnishing rare atropoisomeric C2-arylated indoles. Kinetic studies and DFT computation revealed an uncommon mechanism for this asymmetric transformation, with the oxidative addition being the rate- and enantio-determining step. Excellent stereoselectivities were reached (up to 96% ee), while using an unusual N-heterocyclic carbene ligand bearing an essential remote substituent. Attractive dispersion interactions along with positive C–H-π interactions exerted by the ligand were identified as key factors to guarantee the excellent enantioselection.
Recyclable and reusablen-Bu4NBF4/PEG-400/H2O system for electrochemical C-3 formylation of indoles with Me3N as a carbonyl source
Cheng, Didi,Li, Jingyi,Li, Yujin,Ling, Fei,Liu, Lei,Liu, Tao,Zhong, Weihui
supporting information, p. 4107 - 4113 (2021/06/17)
A safe, practical and eco-friendly electrochemical methodology for the synthesis of 3-formylated indoles has been developed by the utilization of Me3N as a novel formylating reagent. Stoichiometric oxidants, metal catalysts, and activating agents were avoided in this method, and an aqueous biphasic system ofn-Bu4NBF4/PEG-400/H2O was used as a recyclable and reusable reaction medium, which made this electrosynthesis approach more sustainable and environmentally friendly. This process expanded the substrate scope and functional group tolerance for bothN-EDG andN-EWG indoles. Furthermore, late-stage functionalization and total/formal synthesis of drugs and natural products were realized by means of this route.
Visible Light-Driven C-3 Functionalization of Indoles over Conjugated Microporous Polymers
Zhang, Weijie,Tang, Juntao,Yu, Wenguang,Huang, Qiao,Fu, Yu,Kuang, Guichao,Pan, Chunyue,Yu, Guipeng
, p. 8084 - 8091 (2018/07/30)
Metal-free and heterogeneous organic photocatalysts provide an environmentally friendly alternative to traditional metal-based catalysts. This paper reports a series of carbazole-based conjugated microporous polymers (CMPs) with tunable redox potentials and explores their photocatalytic performance with regard to C-3 formylation and thiocyanation of indoles. Conjugated polymers were synthesized through FeCl3 mediated Friedel-Crafts reactions, and their redox potentials were well regulated by simply altering the nature of the core (i.e., 1,4-dibenzyl, 1,3,5-tribenzyl, or 1,3,5-triazin-2,4,6-triyl). The resulting CMPs exhibited high surface areas, visible light absorptions, and tunable semiconductor-range band gaps. With the highest oxidative capability, CMP-CSU6 derived from 1,3,5-tri(9H-carbazol-9-yl)benzene showed the highest efficiency for C-3 formylation and thiocyanation of indoles at room temperature. Notably, the as-made catalysts can be easily recovered with good retention of photocatalytic activity and reused at least five times, suggesting good recyclability. These results are significant for constructing high-performance porous polymer catalysts with tunable photoredox potentials targeting an efficient material design for catalysis.
